Got my Stalin on release day as well. Still not a fan of nerfs afterwards. We made a decision to spend that steel after all.
Same with Bourgogne - when I got it, I decided to not wait for the Azuma. If they were to nerf Bourgogne now, I would be really pissed.
And since people paid 50 Euros for that steel campaign, I don't see a difference to the Missouri and money-converted FXP anymore.

The problem with these two parts of your statement is not only that WG insists to keep them in the cruiser class.
They also refuse to give a proper definition of "super cruisers". What will be next? They nerf "super battleships" and just target specific ships like Missouri, Musashi or Bourgogne+Jean Bart again?
This way of "class balancing" is not transparent at all.

Where did they state that ?
I think you just made that up.
https://eu.wargaming.net/support/en/products/wows/article/22971/
"Premium ships purchased through the Arsenal can be refunded if no more than one (1) battle was played with the ship.
Coupons used on such purchases cannot be restored. Event-related currency may be refunded as its value in credits."